diff options
Diffstat (limited to 'drivers/clk/mxs/clk-ssp.c')
| -rw-r--r-- | drivers/clk/mxs/clk-ssp.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/clk/mxs/clk-ssp.c b/drivers/clk/mxs/clk-ssp.c new file mode 100644 index 000000000..af7bdbf9e --- /dev/null +++ b/drivers/clk/mxs/clk-ssp.c @@ -0,0 +1,62 @@ +/* + * Copyright 2012 DENX Software Engineering, GmbH + * + * Pulled from code: + * Portions copyright (C) 2003 Russell King, PXA MMCI Driver + * Portions copyright (C) 2004-2005 Pierre Ossman, W83L51xD SD/MMC driver + * + * Copyright 2008 Embedded Alley Solutions, Inc. + * Copyright 2009-2011 Freescale Semiconductor, Inc. + * + * The code contained herein is licensed under the GNU General Public + * License. You may obtain a copy of the GNU General Public License + * Version 2 or later at the following locations: + * + * http://www.opensource.org/licenses/gpl-license.html + * http://www.gnu.org/copyleft/gpl.html + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/clk.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/io.h> +#include <linux/spi/mxs-spi.h> + +void mxs_ssp_set_clk_rate(struct mxs_ssp *ssp, unsigned int rate) +{ + unsigned int ssp_clk, ssp_sck; + u32 clock_divide, clock_rate; + u32 val; + + ssp_clk = clk_get_rate(ssp->clk); + + for (clock_divide = 2; clock_divide <= 254; clock_divide += 2) { + clock_rate = DIV_ROUND_UP(ssp_clk, rate * clock_divide); + clock_rate = (clock_rate > 0) ? clock_rate - 1 : 0; + if (clock_rate <= 255) + break; + } + + if (clock_divide > 254) { + dev_err(ssp->dev, + "%s: cannot set clock to %d\n", __func__, rate); + return; + } + + ssp_sck = ssp_clk / clock_divide / (1 + clock_rate); + + val = readl(ssp->base + HW_SSP_TIMING(ssp)); + val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE); + val |= BF_SSP(clock_divide, TIMING_CLOCK_DIVIDE); + val |= BF_SSP(clock_rate, TIMING_CLOCK_RATE); + writel(val, ssp->base + HW_SSP_TIMING(ssp)); + + ssp->clk_rate = ssp_sck; + + dev_dbg(ssp->dev, + "%s: clock_divide %d, clock_rate %d, ssp_clk %d, rate_actual %d, rate_requested %d\n", + __func__, clock_divide, clock_rate, ssp_clk, ssp_sck, rate); +} +EXPORT_SYMBOL_GPL(mxs_ssp_set_clk_rate); |